In recent years, a touch panel which is called the flat touch panel and the touch window and is possible to make a mobile telephone thin has been developed. Then, the mobile telephone whose surface the touch panel is mounted on, that is, the mobile telephone with the touch panel is beginning to become prevalent.
In the mobile telephone with the touch panel, since the touch panel is mounted on the surface of the mobile telephone, a part of body such as cheek and ear of user may touch the touch panel during a telephone call in some cases. In this case, though user does not intend to touch the touch panel, the mobile telephone carries out the same operation as one which is carried out at a time when user touches the touch panel consciously. For this reason, the following inconvenience is caused.
For example, due to the unconscious touch with the touch panel as mentioned above, the mobile telephone carries out an operation which user does not intend to do and consequently, the telephone call is disturbed. As one of operation modes of the mobile telephone, there is an input standby mode in which the mobile telephone waits for a next handling of a handling unit (such as touch panel). The input standby mode continues due to the unconscious touch with the touch panel as mentioned above. For example, a backlight of a liquid crystal display which is installed on the mobile telephone is lit in the input standby mode. In the case that the input standby mode continues during the telephone call due to the touch of cheek of user or the like with the touch panel as mentioned above, waste that the backlight of the liquid crystal display continues to be lit though the liquid crystal display is not used in the telephone call is caused. As a result, electric power of battery of the mobile telephone is consumed wastefully and then, remaining capacity of the battery decreases, and consequently, an available time when user can use the mobile telephone decreases substantially. Moreover, if the backlight of the liquid crystal display continues to be in a lighting state during the telephone call, temperature of the mobile telephone rises due to heat which is generated by the backlight. Therefore, warmth which user feels at the near of ear makes user feel uncomfortable.
Patent document 1 proposes the following configuration. That is, the patent document 1 discloses a configuration in which it is judged whether user talks on the mobile telephone while user's ear touches a speaker, on the basis of degree of focusing of a camera which is mounted on the mobile telephone. Moreover, the patent document 1 proposes a configuration in which an input from the touch panel is made ineffective, in the case that it is judged that the mobile telephone is in a telephone call mode according to the above configuration for judgment.    Patent document 1: Japanese Patent Application Laid-Open No. 2004-159028    Patent document 2: Japanese Patent Application Laid-Open No. 2002-135369    Patent document 3: Japanese Patent Application Laid-Open No. 1998-065598